CSS layout

Hi guys,

I'm not sure if this is the correct forum to post in, as you can probably see I'm new around here.

I have googled and read a tonne of articles on css and what the best layout is to use. As a beginner in CSS I was wondering if any one would like to offer their opinions? I'm trying to ensure that the site I'm working on is compatible with 98% of the main web browsers people use e.g. IE, Firefox, Chrome etc and I'm not sure what the easiest/best option would be.

Should I be attempting a relative layout, using percentages for widths etc and ems for text size, use pixels or a mixture of both?

Hope this has made sense! I think I am just to the point where I am over-thinking what I'm doing.

Cheers